Java provides a rich set of classes and methods for reading and writing data to and from files. This is known as File Handling and Input/Output (IO) in Java. In this lesson, you will learn the basics of Java File Handling and IO and how to perform common file operations such as reading from a file, writing to a file, and appending to a file.

Creating File Object

The first step in file handling is creating a File object. You can do this using the File class in the java.io package. For example, the following code creates a File object for a file named "example.txt" in the current directory.

Check file exists

Once you have a File object, you can perform various file operations using the methods provided by the File class. For example, you can check if a file exists using the exists() method.

Read data from a file

To read data from a file, you can use the FileReader class. This class provides a way to read data from a file character by character. For example, the following code reads the contents of a file named "example.txt" and prints it to the console:

Write data to a file

To write data to a file, you can use the FileWriter class. This class provides a way to write data to a file character by character. For example, the following code writes the text "Hello, World!" to a file named "example.txt":

Append data to a file

If you want to append data to an existing file instead of overwriting it, you can use the FileWriter class with the true argument, as shown in the following example:

In addition to the FileReader and FileWriter classes, Java also provides the BufferedReader and BufferedWriter classes, which provide a more efficient way to read from and write to files. These classes use a buffer to store data, which helps to reduce the number of disk I/O operations and improve the performance of your file I/O operations.

Conclusion

Java provides a rich set of classes and methods for file handling and IO, making it easy to perform common file operations such as reading from a file, writing to a file, and appending to a file. Using these classes, you can read and write data to and from files simply and efficiently.